No problem

What effect do you want?

http://cuihuanhuan.github.io/xxx/ The result is to convert md to html

I found the answer myself, thank you all.
Maybe it’s an editor problem. I'll post something I wrote later on my blog.

Don’t use Cmd Markdown to write your blog! The process of building a blog was the first time I came into contact with markdown. At that time, I used Cmd Markdown, which was recommended by someone online. After writing it, I used jekyll to run it locally or upload it to GitHub, but I found that it could not be parsed. It was really hard for me at the time, and I spent a long time looking for the reason... Later I realized that only this new blog file could not be parsed, and everything else was normal, so I decided to change the editor to MarkdownPad 2 and it was fine. It was really embarrassing! (I tested it again today, June 8th and found it is still the same...)